This invention relates to methods for preparing amidinoureas (also named as carbamylguanidines, carbamoylguanidines, guanylureas or aminoiminomethylureas) and more particularly to processes for preparing bis(amidinoureas) using isothiobiurets as intermediates.
Substituted amidinoureas, i.e., compounds having the formula ##STR1## wherein: Z is an aliphatic, alicyclic or aromatic group and R is hydrogen or an aliphatic group, have been prepared in several ways. These compounds can be prepared, for example, by reacting ioscyanates of the formula Z--N.dbd.C.dbd.O with substituted guanidines of the formula ##STR2## under conditions well known to those skilled in the art. Such a process is disclosed in Curd, F. H. S.; Davey, D. G.; and Richardson, D. N.; J. Chem. Soc. 1949, 1732-1738.
A process of this type for the case wherein R.dbd.H is disclosed in Walls, U.S. Pat. No. 3,539,616, issued Nov. 10, 1970. Monosubstituted amidinoureas of the formula ##STR3## have been prepared by ammonolysis of substituted 4-alkyl-4-isothiobiurets, as described in British Patent 1,194,835.
Curd, F. H. S.; Davey, D. G.; Richardson, D. N.; and Ashworth R. deB., J. Chem. Soc. 1949, 1739-1745, disclose the reaction of 1-(p-chlorophenyl)-4-methyl-4-isodithiobiuret with isopropylamine neat or in methanol, and the reaction of 1-(p-chlorophenyl)-4-methyl-4-isodithiobiuret with methylamine in methanol. No reactions of isothiobiurets and no reactions using diamines are disclosed. In particular, since Curd, et al, did not consider the synthesis of bis(amidinoureas) starting from aliphatic diamines, this reference contains no disclosure of the problems which arise in the synthesis of bis(amidinoureas) and no disclosure of the critical properties of the solvent.
Thus, there are no disclosures in the literature which describe the difficulties which arise in synthesizing bis(amidinoureas) having the formula ##STR4## wherein Z is an aliphatic or alicyclic group and Y is a divalent aliphatic, alicyclic, or heterocyclic radical or combination thereof.
If the reagents and solvents used in synthesizing such bis(amidinoureas) are not carefully chosen the reaction may proceed very slowly or not at all and it may be difficult to isolate the desired product.